Question

How do you factor `2x^2-10x-42`?

Answer 1

Factor `f(x) = 2x^2 - 10x - 42`

Explanation:

`f(x) = 2y = 2(x^2 - 5x - 21).`
The trinomial `y = x^2 - 5x - 21` can't be factored because its determinant `D = b^2 - 4ac = 25 + 84 = 109` is not a perfect square.
Therefor: `f(x) = 2(x^2 - 5x - 21).`